Hardy Environmental Services - Corporate - Frequently Asked Questions: Crawlspace Encapsulation

Rot in wooden framing members

How much does the crawlspace encapsulation system cost?

Every situation is different, but generally the cost to encapsulate a crawlspace ranges from $3 to $5 per square foot range. The cost depends on if a subsurface drainage system is required and the number of dividing walls and support pillars in the crawlspace. This may seem like a lot of money when compared to the cost of new windows, patio furniture or something that you can see or show your friends. Unfortunately it’s underneath your home. But when you consider the long term savings you will realize in energy costs and the protection you gain from water damage and mold, the Cleanspace® is well worth the investment.

How do I know if my crawlspace needs a drainage system?

Standing water in your crawlspace is a tell-tale sign. There are two sources of moisture problems in crawlspaces: (1) groundwater/surface water infiltration and (2) condensation. Homes built near bodies of water often have high groundwater tables and/or poorly drained soils. A drainage system is usually required in these circumstances. In addition, poor grading around the foundation or roof drains that discharge near the foundation are sources of water intrusion into the crawlspace.

Condensation is caused by the mixing of outside air with crawlspace air. Differences in temperature and relative humidity cause condensation to form on floor joists and other surfaces where mold can grow. Un-insulated duct work in the crawlspace also is a cause of condensation. Usually, condensation problems are solved with the installation of the crawlspace liner system and an anti-back flow air supply line.

How does the crawlspace get "conditioned" air?

Very little conditioned air is required for the crawlspace once the vents are closed and the liner is installed. The closed crawlspace is conditioned by means of 4-inch duct that delivers about 35 CFM (cubic feet per minute) of conditioned air from the supply plenum whenever the air handler is running. For comparison, a 12” diameter table top fan puts out about 1,000 CFMs on low speed. The extra air in the crawlspace simply exfiltrates through the crawlspace wall near the sill plate. No fan timing or fan recycling device or stand alone dehumidifiers are needed to control moisture. For homes with electric baseboard heat, a small fan with a anti-backflow butterfly damper draws air from the indoor environment and distributes it to the crawlspace. The backflow damper prevents crawlspace air from entering the home when the fan is off.

How can crawlspace mold can get into my living quarters?

The scientifically proven “stack effect” describes the movement of air from the lower portions (crawlspace/basement) of a home to the higher portion of the home (attic). Air is easily transferred from the crawlspace to the living areas of the house. Studies have shown that more than 20% of the air in the home comes from the crawlspace. Damp or wet crawlspaces usually have high levels of viable (living) respirable mold spores. Mold laden crawlspace affects asthmatics and people with allergies. More than 20 million Americans have been diagnosed with asthma, including more than 6 million children under the age of 18.

Does my insulation have to be replaced?

It depends on the condition of the insulation. Typically, we find most crawlspace have been insulated with insulation batts between the floor joists. If the insulation has been subjected to repeated wetting and drying conditions over a period of several years, then it’s R value (thermal resistance) diminishes dramatically. Our liner system includes the installation of 2” thick R-13 rated polyisocyanurate foam panels on the foundation perimeter walls, beneath the liner, and on the band joist.

Is the work guaranteed?

Our workmanship is guaranteed for one year. The liner is guaranteed for 25 years against rips and tears.

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